The catastrophic breach of a major NATO base in Afghanistan and killings by turncoat local forces are spurring concerns about the pace and strategy of the U.S. military pullout, including the end last week of the surge of extra troops.

The spectacle of brazen suicide attacks like the Sept. 14 assault on Camp Bastion and a demoralizing spate of insider killings of Marines and other service members signaled a change in insurgent tactics as U.S. troop levels fell from a high of about 100,000 to 68,000.

Troubling as those developments are, however, several defense analysts concurred with military commanders who say they will not derail the U.S.-led coalition’s long-term exit strategy for the unpopular war — a handoff of security responsibility to Afghan troops and the departure of most conventional foreign troops by late 2014.

The Afghan national security force, which Defense Secretary Leon Panetta describes as the “defeat mechanism” of the insurgency, has more than doubled in size since November 2008 to upward of 330,000. As the number swells toward a goal of 352,000, Afghan soldiers and police have killed a record high 51 international troops this year.

Some members of the Senate Armed Services Committee blamed a rush to train recruits on the increase in insider killings and called for everything from a “strategic pause” in the drawdown to an early withdrawal.

As violence flared across the Middle East and Afghanistan over a video clip denigrating the Prophet Muhammad, NATO commanders suspended lower level partnered operations between coalition and Afghan troops and re-evaluated vetting and force protection measures. Normal partnered operations have since resumed, Panetta announced Thursday.

Even if U.S. forces keep their guard up, some question whether the insider killings cast the entire endgame for the war in doubt.

“I wouldn’t want to be over there and serve side-by-side with an unvetted Afghan force,” said U.S. Rep. Duncan Hunter, R-Alpine, a Marine combat veteran on the House Armed Services Committee. “If Plan A was to partner with the Afghan forces, and you now say we can’t trust the Afghan forces … that plan is shot to hell. So what’s the next plan? That’s what the president and our military leaders need to come tell us.”

In what has been the deadliest area of the country for them, international troops under the command of a Camp Pendleton general have been forced by the rapid drawdown to push their Afghan counterparts into increasingly independent operations in much of Helmand province.

As the number of Marines fell from a high of more than 20,000 last year to less than 8,000 now, the Americans shifted in many places toward a “tactical overwatch” stance operating adjacent to Afghan units instead of mixing among them.

In central Sangin, Marine infantrymen still enable Afghan forces by providing them with resources such as medevac flights and equipment to counter improvised explosive devices, said Lt. Col. David Bradney, commanding officer of 1st Battalion, 7th Marine Regiment out of Twentynine Palms.

But this summer the infantry unit changed its ratios to force the Afghans to take the lead for most operations in those more secure central areas: “we will not go on patrol if we outnumber them. … If you bring six, we will bring six. That is the most we will do.”